Chair iron



June 1, 1937. E. c. Kl-:YwoRTH s 2,082,499

Filed May 25, 1934 Patented `lune 1', 1937 UNITED sTATEs PATENT OFFICE CHAIR IRON Application May 25, 1934, Serial No. 727,482

8 Claims.

Chair irons for tilting oflice chairs and the like are commonly provided with one or more springs designed to more or less counterbalanceV the weight of the occupant of the chair so as to make it easy for him to tilt the chair as desired, the springs acting vto cushion the tilting motion and to return the chair to its normal upright position when the occupant rises. The service to which these springs is subjected is found in time to render them brittle, so that they are liable to break suddenly. As heretofore constructed and arranged, the breaking of a spring causes the spring to lose its counterbalance effect almost, if not quite entirely, allowing the occupant of the chair to lurch backwardly with considerable violence and sometimes causing the chair to upset with resultant danger of injury to the occupant.

One of the objects of the present invention, therefore, is to provide means for holding the parts of the spring on breaking in axial alinement so that breakage in one place causes the spring length to shorten by a single convolution. I'he counterbalancing of the spring is then only slightly lessened, the broken parts snapping together so suddently that the occupant of the chair experiences no noticeable shock.

A further desirable result which may be accomplished by the holding means of this invention is to additionally cushion the nal portion of the tilting motion of the chair so that it'comes to its limit of backward tilting movement without shock or jar. Y

For a more complete understanding of this invention, reference may be had to the accompanying drawing in which Figure 1 is a top plan of a chair iron embodying this invention.

Figure 2 isa detail section on line 2-2 of Figure 1. v

Figure 3 is a detail section on line 3-3 of Figure 2.

Figure 4 is a view similar to a portion of Figure 2, but to a smaller scale and showing a modication.

Figure 5 is a fragmentary view partly in section showing the chair at its rear limit of tilting and showing the construction of` Figure 2.

Figure 6 is a fragmentary side elevation showing the position of the associated parts on breaking of a spring when this invention is employed.

Referring to the drawing, at I is indicated a substantially U-shaped member, to-opposite 4arms of which are shown as rsecured by rivets 2, the angle-shaped bars 3, the upper flanges 4 of which are provided with holes 5 by which these angle members may be secured to a chair seat 6, as shown in Figure 5. The member I is also provided with a pair of spaced ears 3 through which may extend a pivot 9 about which the chair may tilt. This pivot 9 secures the parts attached to the seat 6 to other parts secured to a chair base. These other parts as shown comprise a U-shaped member I0 through the sides I I of which the pivot 9 passes. This member Il), together with a reinforcing top piece I2 which may be of inverted U-shape with its side portions I2a lapping the sides I I of the member I0 and secured thereto as by rivets |20, are shown as secured to the upper end of the chair base standard I4. The Wall member constituting the base I5 of the U-shaped member I, which is substantially perpendicular to the chair seat, is shown as provided with a pair of seat portions I6 against which are seated the inner ends of a pair of coil springs Il. The outer ends of these springs I1 bear against a seat member I8 which has a rim I9 enclosing the ends of these springs.l Between the springs a rod 20 is extended through the member I8 and is provided with a head 2| vat its rear end. The forward end of the rod 20 passes through an abutment piece 22, the ends of which bear against edge projections 23 at the sides of thev U-shaped member Ill. The rod 20 thus extends eccentric to the pivot 9 so that when the chair is tilted rearwardly, as shown in Figure 5, the spring seat member I8 is brought toward the member I5, thus additionally compressing the springs between these parts. The outer end portion of the rod 20 is threaded as at 25 and has placed thereon a lock washer 26 bearing against the member 22 and an adjusting nut 2l which may have a hand wheel 28 (see Figure 5) on its outer end. By turning the wheel 28 the tension of the springs Il may be adjusted toV suit the requirements of the occupant of the chair, the springs more or less counterbalancing his Weight as he tilts the chair rearwardly. This mechanism so far described is old and Well known in the art.

It will be noted that should one of the springs l1 break, in the absence of some further mechanism, it might drop out from between its spring seats so that it would be no longer effective to cushion the rearward tilting of the chair. Such breakage will usually occur as the occupant is tilting rearwardly and if no means were taken to prevent it, this would result in the cushioning and counterbalancing eiect of the broken spring to beV suddently released, thus permitting the chair to tilt back violently suddenly and perhaps to an extent suiflcient to cause the chair to upset. Such a possibility is prevented by the present invention, means being provided to hold either of the springs which may break in such a manner that it cannot fall out of place but must continue to exert a counterbalancing eiort, even though it is somewhat reduced by the breakage.

This means may comprise a member arranged substantially coaxially of each of the springs, and as shown this member is a core 38 of such an external diameter slightly less than the internal diameter of the spring that when a spring breaks, it holds the broken parts in substantially axial alinement, as shown in Figure 6, in which the parts 30a. and 30h of the broken spring are held in operative relation, the coils, however, collapsing on each by a single convolution at the break, bringing the parts a and b and c and d, respectively, into contact. For a purpose which will later appear this core member is preferably of yieldable material such as rubber.

In Figures 2 and 5 the core is shown as provided at its inner end with a portion 3l of reduced diameter beyond which is a head 32. The inner end of the core is recessed at 33 so as to permit the head 32 to be compressed sufficiently to be passed through the hole 34 in the seat portion I6, whereupon the head 32 may be released so as to expand on the inner side of the member I5 and hold the core in position.

Another means of supporting the core is shown in Figure 4 in which a pin 35 is passed through the seat member I 6 and riveted over on its inner face, the core member being then in the form of a tube or sleeve 36, which may be placed over the pin 35. This figure shows, also, an external sleeve 31 secured to the member I5 and which also has the function of holding broken portions of the spring in alinement, and either this sleeve or the core may be used alone for this purpose if desired.

By making the core member of yieldable material, such as rubber, it may have another useful function besides its support of the broken parts of the spring. As shown in Figures 1, 2, 4 and 6, this core member is somewhat shorter than the normal distance between the spring seat portions, even when they are adjusted by manipulation of the han-d wheel 28, and the extent to which it is shorter may be so proportioned that just before the chair reaches its rearward limit of tilting at which the member I5 engages a portion of the member Ill, these parts constituting tilting limiting means, the end of the core member contacts with the seat member I8 and is compressed as the seat member is tilted to its extreme backward limit. Thus this core member acts as a cushioning element, increasing the resistance to rearward tilting of the chair near its tilting limit, thus acting to bring it to rest in its limit of backward tilting Without shock or jar to the occupant.

From the foregoing description of certain embodiments of this invention, it should be evident to those skilled in the art that various changes and modifications may be made without departing from the spirit or scope of this invention as defined by the appended claims.

I claim:

l. A chair iron comprising members for securement to a chair seat and to a base, respectively, said members being pivoted together to permit tilting of said seat with respect to said base, means including a coil spring yieldingly holding said members in non-tilting position, a resilient core within said spring and of slightly less diameter than the internal diameter of said spring effective when said spring breaks to hold the broken parts of said spring in substantially coaxial and operative condition, and an element engaging with said core near the limit of tilting motion of said members to further cushion the nal tilting motion thereof.

2. A chair iron for a tilting chair, comprising parts pivoted together for attachment to the chair seat and to the chair base, respectively, one of said parts having a spring seat, a coil spring having one end engaging in said spring seat, a member having a spring seat engageable with the other end of said spring, means engaging said member and the other of said parts eccentric to the pivot between said parts for adjusting the tension of said spring and tending to hold said chair seat in non-tilted position, and a resilient core member within said spring and of a diameter slightly less than the interior of said spring and effective when said spring breaks to hold the broken parts of said spring substantially coaxial, said core being of a length to be compressed between said spring seats when said chair is near its limit of backward tilting and out of contact with one of said spring seats at all other times.

3. A chair iron for a tilting chair, comprising parts pivoted together for attachment to a chair seat and base, respectively, one of said parts having a pair of spaced spring seats, a pair of coil springs each having one end seated on one of said spring seats, a member having a pair of spring seats for engagement with the other ends of said springs, means securing said member to the other of said parts eccentric to ,said pivot, whereby said springs yieldingly hold said chair in non-tilted position, and a core of yieldable material within each of said springs and of slightly less diameter than the inside of its respective spring and of a length suicient to cause axial compression thereof when said chair has been tilted to al predetermined extent, but insuflicient to cause compression thereof when said chair is untilted.

4. A chair iron for a tilting chair, comprising parts pivoted together for attachment to a chair seat and base, respectively, one of said parts having a pair of spaced spring seats, a pair of coil springs each having one end seated on one of said spring seats, a member having a pair of spring seats for engagement with the other ends of said springs, means securing said member to the other of said parts eccentric to said pivot, whereby said springs yieldingly hold said chair in non-tilted position, and a core of yielding material within each of said springs and of slightly less diameter than the interior of its respective spring and secured to one of said spring seat portions, said cores being spaced from the other spring seat when the chair is in a non-tilted position and of lengths to be compressed between said spring seats when the chair is tilted to a predetermined extent.

5. In combination, a chair iron for a tilting chair, comprising parts pivoted together for attachment to a chair seat and base, respectively, one of said parts having a pair of spaced spring seats, a pair of coil springs each having one end seated on one of said spring seats, a member having a pair of spring seats for engagement with the other ends of said springs, means securing said member to the other of said parts eccentric to said pivot, whereby said springs yieldingly hold said chair in non-tilted position, posts secured at one end to one of said spring seat portions substantially concentric with said springs, and a tube of yieldable material carried by and surrounding each of said posts and projecting toward the other of said spring seat portions and of suicient external diameter to hold, when its spring breaks, the broken portions of the spring in substantially coaxial and operative relation.

6. In combination, a chair iron for a tilting chair, comprising parts pivoted together for attachment to a chair seat and base, respectively, one of said parts having a pair of spaced spring seats, a pair of coil springs each having one end seated on one of said spring seats, a member having a pair of spring seats for engagement with the other ends of said springs, means securing said member to the other of said parts eccentric to said pivot, whereby said springs yieldingly hold said chair in non-tilted position, posts secured at one end to one of said spring seat portions substantially concentric with said springs, and a tube of yieldable material carried by and surrounding each of said posts and projecting toward the other of said spring seat portions and of suiflcient external diameter to hold, when its spring breaks, the broken portions of the spring in substantial coaxial and operative relation, said tubes being of a length sucient to be compressed between the spring seats for its respective spring as said chair approaches the limit of its backward tilting movement.

7. A chair iron comprising a wall member, means for securing said wall member to the lower face of a chair seat and substantially perpendicular thereto, a base member pivotally secured to said means on one side of said wall member, a coil spring engaging said wall member at one end, an element engaging the opposite end of said spring and operatively connected to said base member to cause said spring to yieldingly hold said seat in non-tilted position and to more or less counterbalance the Weight of the occupant of the chair seat as said seat is tilted, and a resilient bumper secured to said wall member and engageable with said element when said seat is tilted to a predetermined amount and extending coaxially within said spring and of a diameter slightly smaller than that of the inside of said spring to act when said spring breaks to hold the broken parts in substantially coaxial relation and maintaining them effective to partly counterbalance the Weight of the chair occupant as said chair is tilted.

8. A chair iron comprising a wall member, means for securing said wall member to the lower face of a chair seat and substantially perpendicular thereto, a base member pivotally secured to said means on one side of said wall member, a coil spring engaging said wall member at one end, an element engaging the opposite end of said spring and operatively connected to said base member to cause said spring to yieldingly hold said seat in non-tilted position and to more or less counterbalance the weight of the occupant of thel chair seat as said seat is tilted, a resilient bumper secured to said wall member and extending coaxially within said spring and of a diameter slightly smaller than that of the inside of said spring to act when said spring breaks to hold the broken parts in substantially coaxial relation and maintain them effective to partly counterbalance the weight of the chair occupant as said chair is tilted, and stops to limit the tilting of said seat, said bumper being of a length to engage said element and be coml pressed when said seat approaches its tilting limit.

EDWARD C. KEYWORTH. 

